It is generally known in the art of internal combustion engine design to use fuel rails to deliver fuel to individual fuel injectors. A fuel rail is essentially an elongated manifold connected to a fuel supply system and having a plurality of ports for mating in any of various arrangements with a plurality of fuel injectors to be supplied.
Typically, a fuel rail assembly includes a plurality of fuel injector sockets in communication with the fuel rail, the injectors being inserted into the sockets and held in place in an engine cylinder head or intake manifold by bolts securing the fuel rail assembly to the head or manifold.
Two types of fuel delivery systems exist, the return type system including a return pipe to the fuel supply system and the return-less system. In what is referred to as a return-less system, a fuel return line does not fluidly connect the fuel rail back to the fuel supply system at a rail outlet end. In a “return” system, a fuel line fluidly connects the end of the fuel rail opposite the inlet end back to the fuel supply system. For economic reasons, the use of return-less fuel delivery systems increased in recent years. Drawbacks with return-less fuel delivery systems arise from pressure pulsations and fuel reflecting waves generated during reciprocating movements of a fuel pump and fuel injector valve assemblies.
During operation of an internal combustion engine, fuel rail assemblies typically vibrate due to the reciprocating movements of a fuel pump and fuel injector valve assemblies. For example, opening and closing events of the fuel injectors create pressure waves in the fuel system. To absorb the pressure waves, flexing walled manifolds are often used as a fuel rail or internal dampers are installed within the fuel rails. While flexing walled manifolds are less expensive than internal dampers and do not require additional parts to be installed the amount of noise typically radiated by the fuel rail increases with the use of flexing walls. Such noise radiated by the fuel rail assembly is objectionable and undesirable.
One prior art approach to dampen the noise radiated by a fuel rail assembly during operation of an internal combustion engine includes placing an acoustic cover on top of each fuel rail. While this method may be effective to reduce fuel system noise, the acoustic cover is a separate part that needs to be manufactured and installed, which creates extra cost and requires additional cycle time. In modern engine design it is desirable to reduce the number of parts required in the assembly of a fuel injection system in order to reduce the manufacturing cost, cycle time, and to improve reliability of the engine.
Another prior art approach to dampen the noise radiated by a fuel rail assembly during operation of an internal combustion engine includes integration of stiffening ribs or cavities that are aligned perpendicular to the axis of the fuel rail. Panels formed between these ribs or cavities may have a relatively large surface area and, therefore, may still allow vibration of the fuel rail assembly and, consequently, noise radiation by the fuel rail assembly.
What is needed in the art is a more effective fuel rail radiated noise reduction that eliminates assembly of additional parts.
It is a principal object of the present invention to provide a modified fuel conduit that enables reduction or elimination of radiated frequency noise for a variety of fuel systems.